This invention relates to compositions useful in the treatment of siliceous surfaces. More particularly it relates to one-part compositions which clean and activate siliceous surfaces and impart durable hydrophilicity to said surfaces.
Although various types of compositions have been suggested for use in imparting hydrophilicity to various substrates, all of such previously suggested materials have been less than desirable for one reason or another. For example, some of the earliest suggested compositions for such use comprised anionic or non-ionic surfactants (e.g., triethanolammonium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyalkylene sorbitol). These surfactants have been described for use in either solid or aqueous solution form. However, the major disadvantage associated with the use of such compositons is that the hydrophilicity and antifogging properties imparted by the surfactants simply do not exhibit very good durability during use, (i.e., they are easily dissolved by water and removed from the surface). Consequently, in order for such compositions to be effective they must be reapplied to the surface at frequent intervals.
Another type of surfactant which has been described for use in imparting hydrophilic properties is one containing a terpolymer of dimethyl silicone, polyethylene oxide, and polypropylene oxide. This type of surfactant, which is described, for example, in U.S. Pat. 3,337,351, suffers from the same drawbacks as discussed above, namely easy dissolution by water.
Still another type of surface active agent is described in U.S. Pat. No. 3,187,033. This type of material contains S--C bonded sulfo groups and displays physical and chemical properties similar to soaps. Thus, for example, these materials exhibit substantial surface tension lowering capabilities.
U.S. Pat. No. 3,507,897 describes siloxane surface active agents in aqueous media. These solutions preferably have a pH of from 5 to 8 so that the agents do not degrade. Additionally, these agents are said to exhibit excellent surface tension lowering capabilities.
U.S. Pat. No. 3,328,449 describes sulfopropylated, organofunctional silane and siloxane materials which are useful as detergents, ion exchange resins, wetting agents, anti-stat agents and polymerization catalysts for siloxanes. It is said that these materials may be provided in solution form and that suitable solvents include water. However, it is also said that such solvents must not react with the solute. There is no discussion therein of stable aqueous solutions of sulfonato-organosilanols or of siliceous surfaces rendered hydrophilic by treatment therewith.
U.S. Pat. No. 3,455,877 describes organosilicon epoxides wherein the epoxy group (or the radical containing the epoxy group) is attached to silicon by a Si-C linkage. These materials are said to be useful as emulsifiers, plasticizers, lubricants, etc. They are also said to be useful in preparing hydroxy sodium sulfonates by reacting the epoxides with sodium sulfite. There is no discussion of the preparation of stable aqueous solutions of such compounds or of the durably hydrophilic surfaces produced by contacting such compositions with siliceous surfaces.
The present invention provides compositions which are useful for cleaning, activating and imparting durable hydrophilicity to siliceous surfaces. The compositions of the present invention are particularly useful in imparting hydrophilicity to surfaces where easy grease and wax removal is desired or required. Thus, for example, the compositions are useful in treating glass surfaces such as household windows, automobile windshields and windows, eyeglasses and bathroom mirrors; glazed ceramic surfaces such as ceramic tile and ceramic bathroom fixtures and enamelled iron surface.
Siliceous surfaces treated in accordance with the present invention are not rendered grease or wax repellent, (i.e., they are not made oleophobic). Consequently, greases and waxes may attach to the treated surfaces. However, the treated surfaces are rendered readily cleanable so that grease and wax may be removed therefrom by simple water rinsing alone although very light rubbing may also be helpful in some instances.
Because the composition of the present invention impart durable hydrophilicity to siliceous surfaces, such surfaces may be readily cleaned even after having been repeatedly previously soiled or marked by grease or wax and then cleaned. Moreover, the treated surfaces are substantially easier to clean than are surfaces which have not been so treated.
Examples of greases and waxes which have been found to be readily removable from surfaces treated in accordance with the present invention are butter, margarine, lard, natural sebum (skin oil), artificial sebum, motor oils, motor greases, paraffin wax and wax pencil marks. Still other substances such as elastomer-based adhesives, pressuresensitive adhesives, thermoplastic (solvent soluble) adhesives, thermosetting adhesives, epoxy adhesives, silicone based adhesives, etc., are readily removable from surfaces treated in accordance with the present invention.
The compositions of the present invention comprise aqueous solutions of a sulfonato-organosilanol compound. Surprisingly, such compositions are stable over long periods of time even at relatively high concentrations of the sulfonato-organosilanol compounds (e.g., 10% to 15% by weight). Thus, the treatment activity of the compositions is retained and no precipitate of the silanol compound is formed therein upon prolonged storage. Moreover, various concentratons of the sulfonato-organosilanol compounds may be employed in the compositions of the invention.
Additionally the preferred compositions of the invention provide thin, durable antifogging coatings on the siliceous surfaces. Thus individual water droplets will not form and remain on surfaces treated with said solutions (i.e., said surfaces do not fog over) despite repeated exposures to conditions of high humidity.
Surprisingly the foregoing results are achieved even though the sulfonato-organosilanol compounds employed do not exhibit typical surfactant characteristics. Thus these compounds have no significant effect upon the surface tension of aqueous media. Moreover these results are provided even though the compositions of the invention also clean and activate the siliceous surface while at the same time rendering it hydrophilic.